You’d need to add a new rule to the theme’s style sheet. I recommend installing the Firebug add on for Firefox or using Chrome’s Firebug Lite which will enable you to right click on any element to inspect it and determine the associated style rules or the selectors required to create new style rules.

I just did that using the Font Uploader plug-in and the stylesheet (like Sozo said…he rocks, btw). I found the element and then put it into the Font Uploader…worked perfectly. Then I played with the code to change the case and the size. Voila!